I tried out the new DartPad!

main.dart

import 'dart:math' as math;

import 'package:flutter/material.dart';

final dscTeam = [
  {
    'name': 'Viviana Sutedjo',
    'nickName': 'Vivi',
    'color': getRandomColor(),
  },
  {
    'name': 'Berzan Yildiz',
    'nickName': 'Berzan',
    'color': getRandomColor(),
  },
  {
    'name': 'Florian Müller',
    'nickName': 'Flo',
    'color': getRandomColor(),
  },
  {
    'name': 'Andreas Zimmerer',
    'nickName': 'Andi',
    'color': getRandomColor(),
  },
];

final guests = [
  {
    'name': 'Vince Varga',
    'nickName': 'Vince',
    'color': getRandomColor(),
  },
];

// Simple Dart function
Color getRandomColor() {
  return Color((math.Random().nextDouble() * 0xFFFFFF).toInt()).withOpacity(1);
}

class DscList extends StatefulWidget {
  @override
  createState() => DscListState();
}

class DscListState extends State<DscList> {
  final Map<String, int> tapCount = {};

  @override
  initState() {
    super.initState();
    List.from(dscTeam)
      ..addAll(guests)
      ..forEach((m) {
        tapCount[m['name']] = 0;
      });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: ListView(
          padding: const EdgeInsets.all(16),
          children: <Widget>[
            Text('DSC Team', style: Theme.of(context).textTheme.title),
            for (var t in dscTeam)
              PersonTile(
                name: t['name'],
                nickName: t['nickName'],
                color: t['color'],
                onTap: () => handleTap(t['name']),
                count: tapCount[t['name']],
              ),
            Text('Guests', style: Theme.of(context).textTheme.title),
            for (var g in guests)
              PersonTile(
                name: g['name'],
                nickName: g['nickName'],
                color: g['color'],
                onTap: () => handleTap(g['name']),
                count: tapCount[g['name']],
              ),
          ],
        ),
      ),
    );
  }

  handleTap(name) => setState(() => tapCount[name]++);
}

class PersonTile extends StatelessWidget {
  const PersonTile({
    @required this.name,
    @required this.nickName,
    @required this.color,
    @required this.count,
    @required this.onTap,
  });

  final String name;
  final String nickName;
  final int count;
  final Color color;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    return ListTile(
        leading: CircleAvatar(
          child: Text(name[0]),
          backgroundColor: color,
        ),
        title: Text(name),
        subtitle: Text(nickName),
        trailing: Text('$count'),
        onTap: onTap);
  }
}

// Arrow
void main() => runApp(DscList());